AJP - Heart and Circulatory Physiology, Vol 249, Issue 2 293-H299, Copyright © 1985 by American Physiological Society
Mechanism for dynamic changes in stenotic severity
D. R. Higgins, W. P. Santamore, A. A. Bove and P. Nemir Jr
The mechanism responsible for rapid changes in stenotic severity or
resistance due to alterations in perfusion pressure and distal resistance
is addressed by this study. An in vitro, eccentric arterial stenosis model
was created using 15 canine carotid arteries cannulated with silicone plugs
containing special pressure-transducing catheters designed to measure
pressure directly, within the stenosis. The vessels were perfused at
perfusion pressures of 150, 100, and 75 mmHg and at two levels of distal
resistance while perfusion pressure, distal pressure, stenotic pressure,
and flow were recorded. Orthogonal arteriograms were performed. Stenotic
resistance was calculated as (perfusion pressure--distal pressure)/flow.
All variables changed significantly (P less than 0.05) with decreases in
perfusion pressure. Stenotic resistance always increased (P less than 0.02)
as perfusion pressure or distal resistance decreased. These dynamic changes
in stenotic resistance occurred at stenotic pressures well above the
atmospheric, extraluminal pressure. Arteriographic data demonstrated
decreasing stenotic luminal area with decreasing stenotic pressure. These
results confirm the assertion that rapid changes in stenotic resistance are
related to changes in stenotic luminal area and are not due to extrinsic
forces. The principles of the Starling resistor are, therefore, not
applicable to dynamic arterial stenoses. This information is immediately
relevant to clinical situations in which complaint, severe stenosis results
in ischemia.
